Dual-tube drill string for sample drilling



Nov. 3, 1964 G. HUNT ETAL DUAL-TUBE DRILL STRING FOR SAMPLE DRILLING 2 Sheets-Sheet 1 Filed Aug. 4, 1961 INVENTOR. LAWRENCE G. HUNT HOWARD A WILMETH ATTORNEYS Nov. 3, 1964 G. HUNT ETAL DUAL-TUBE DRILL STRING FOR SAMPLE DRILLING 2 Sheets-Sheet 2 Filed Aug. 4, 1961 INVENTOR. LAWRENCE G. HUNT HOWARD A. WILMETH 3% :2. //1

ATTORNEYS United States Patent 3,155,179 DUAL-TUBE DRILL $6 FOR SAMPLE DRILLENG Lawrence G. Hunt, Tucson, Ariz., and Howard A. Wilmeth, Silver (Iity, N. Men, assiguors to Kennecott Copper Corporation, New York, N.Y., a corporation of New York Filed Aug. 4, 19-61, Ser. No. 129,458 9 Claims. ((31. 175-215) This invention relates to rotary drilling apparatus and particularly to drill strings therefor which are adapted to yield samples of the formation being drilled. It is concerned with improvements to existing types of dual tube drill strings for use with both core drilling rigs and rotary well drilling rigs.

In core drilling practice it is customary to utilize a single string of tubing extending downwardly from the surface and an inner core barrel extending upwardly within such tubing from the bit, with a wire cable extending from such barrel to the surface. Drilling is stopped periodically while the core barrel is retrieved from the bottom of the hole by means of the Wire cable.

Dual tube drill strings have been proposed heretofore in connection with rotary rigs in order to enable continuous retrieval of core samples as the drilling proceeds continuously. U.S. Patent Numbers 1,071,199 and 2,657,- 016 to B. Andrews and D. B. Grable, respectively, are representative. Both utilize a fiuid, introduced into an outer string of tubing, to propel the core samples upwardly through a string of smaller diameter tubing placed concentrically within the outer string, and both maintain a liquid under pressure in the annular space between the outer drill string and the bore hole to prevent loss of fiuid into such space. In both, the core samples are discharged through a gooseneck continuation of the inner string of tubing at the surface.

A principal object in the making of the present invention was to positively isolate the particular stratum being drilling at any given time from strata already drilled, so accurate and representative samples can be obtained.

This object has been achieved by providing a swiveled seal ring or packer seal exteriorly of the outer drill string above the bit and by establishing localized circulation of pressure fluid below such seal ring or packer and from the annular conductor passage-located between inner and outer strings of tubing-into the space between the bit and the bore hole wall and from such space into the annular conductor passage, whereby drill cuttings will be positively carried into the mainstream of fluid used to propel the cores upwardly through the inner string of tubing to the surface. Disposal of drill cuttings in this manner not only insures effective sampling of strata, but eliminates regrinding of cuttings and excessive bit wear caused thereby.

As one aspect of the invention, it is preferred to provide an annular reamer between the bit and the packer seal ring, for smoothing the bore walls in advance of such ring to insure maximum effectiveness of the latter in establishing a fluid-tight seal. It is highly advantageous that such reamer lie in the path of the aforesaid localized circulation of pressure fiuid, so that a cleaning action will be exerted on the reamer as the drilling progresses.

In accordance with the invention, a removable, rectilinear, core barrel is provided at the upper end of the inner string of tubing to catch and retain cores. This preserves solid core samples intact and avoids the stoppages to be expected with a gooseneck discharge.

A specific embodiment'representing what is presently regarded as the best mode of carrying out the invention 3,155,179 Patented Nov. 3, 196:4

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in actual practice is illustrated in the accompanying drawings.

In the drawings:

FIG. 1 is a view showing the apparatus of the invention in elevation during a drilling operation, portions of the drill string being broken out for convenience of illustration;

FIG. 2, a horizontal section taken on the line 22 of FIG. 1 and drawn to a larger scale;

FIG. 3, a similar view taken on the line 3-3 of FIG. 1;

FIG. 4, a similar view taken on the line 4-4 of FIG. 1;

FIG. 5, a similar view taken on the line 55 of FIG. 1;

FIG. 6, a similar view taken on the line 66 of FIG. 1;

FIG. 7, a similar view taken on the line '7-i of FIG. 1;

PEG. 8, a fragmentary vertical section taken on the line 8-3 of FIGS. 2, 3, and 4, but drawn to a somewhat smaller scale; and

FIG. 9, a similar view taken on the line 99 of FIGS. 5, 6, and 7.

Referring to the drawings:

In the illustrated construction, a dual tube drill string 19, FIG. 1, extend from a swivel mounting an injection head 11, through the earth formation 12 being drilled. to a drill assembly, indicated generally 13. An exhaust housing 14 is removably mounted on injection head 11, and has a rectilinear core barrel 15 extending upwardly therefrom.

The drill string 10 includes an outer or drive string 16, FIGS. 8 and 9, and an inner or core recovery string 17, the individual lengths of pipe making up the two strings being coupled together in the usual manner, as indicated. The inner string 17 terminates at its lower end in a core booster tube 171 and at its upper end in a straight flow connection with the lower end of core barrel 15.

Outer string 16 is rotated by the usual mechanical drive (not shown), this being permitted by the swivel mounting in injection head 11, which is made up of a lower thrust bearing 13, FIG. 8, and an upper bearing 19.

A critical part of the apparatus, so far as the invention is concerned, is the drill assembly 15. In the form illustrated, it is made up of a diamond core bit 20 screwed onto the lower end of a reamer 21, and is secured to the lower end of the outer or drive string 16 by means of a threaded coupling 22.

Provision is made by means of pipe 23, FIG. 8, for introducing a pressure fluid, desirably compressed air, from any suitable source (not shown) into the manifold 24 of injection head 11 and thence through opening 25 into the annular space 26 between outer and inner pipe strings '16 and 17, respectively, for the purpose of elevatingthrough the interior 27 of the inner string-the cores cut by core bit 20.

Passages 28 and 29, FIGS. 1, 7, and 9, through the walls of core bit 26, together with exterior grooves 30, are provided to permit flow of such pressure fluid around and under the outside and nose of the bit and into the interior 27 of the inner pipe string, carrying cuttings therewith. Cores cut by the bit are propelled upwardly, along with the cuttings, through such inner pipe string.

One feature of the invention is the provision of elongate gro0ves 31, FIG. 9, interiorly of and extending along core booster tube 17-1 to provide for more voluminous flow of fluid about the cores being out than would exist otherwise.

These grooves 31 insure the passage of sufiicient air around the nose or tip of the bit to blow out thecuttings while the core is forming, so as to keep the bit clean and cool, and, also, suificient air to insure elevationof the core segments into core-retrieving barrel 15. They preferably have length somewhat greater than the longest solid core segment that is likely to form before breaking off at the bit.

When a segment of core passes the upper ends of the grooves 31, the flow of air is momentarily restricted, building up the pressure about the lower portion of the core segment and separating it from the next lower segment. The void thus formed between the two core segments is supplied with a greater volume of air than that which escapes between the core segment and the wall of the core recovery casing. This increased volume of air maintains a positive pressure on the undersurface of the core segment and propels it rapidly up the core recovery tube 17.

The air is exhausted through an opening 32 in the upper portion of tube 17, which leads into an exhaust chamber 33 and, thence, into discharge piping 34. The solid core segments continue on past exhaust opening 32 and into core barrel 15, progressively, where they collect, awaiting recovery by removal and emptying of such core barrel.

Spring fingers 35 retain the core segments in place while permitting them to be progressively built up from below. A vent opening 36 in the cap 15a of the core barrel insures the provision of air cushions between adjoining core segments to minimize breakage.

As is customary in drilling practice, a drilling mud or the like is utilized to facilitate the operation. introduced into the annular space 37, FIG. 1, between the bore hole and the outside of the outer string or drive casing 16 by any suitable means (not shown). This drilling fluid is not relied upon to cool the bit and carrying the cuttings to the suface. formed by the compressed air introduced through annular space 26, as explained previously.

It is the purpose of the invention to effectively seal off the annular space 37 from the lower continuation 37-1 thereof surrounding the drill assembly, and to provide for localized circulation of pressure fluid therethrough so as to positively remove the cuttings as they are formed, without contamination by infiltration of debris from above.

To this end, a packer seal ring or collar 38 is freely swiveled on the smooth shank 21a of reamer 21 immediately above the reamer flutes 211). As shown, the ring 33 has a rigid body 330, to which is vulcanized a horizontally corrugated facing 38b of rubber or other suitable fiexible and resilient sealing material.

As the drilling progresses, this packer seal ring 38 floats freely on the drill string, hugging the earth walls of the bore hole tightly as the outer or drive string 16 rotates, but descending therewith because of abutment against the lower end of coupling 22.. The position of such ring 38 immediately above reamer flutes 21b insures as smooth as possible earth wall surface for hugging by the rubber facing 38b; thereby contributing significantly to the effectiveness of the sealing action.

In order to establish the desired localized circulation of the compressed air injected at 23, passages 39 are providedv below packer seal ring 38, circumferentially of the drill string. As shown in FIG. 9, these pass through the wall of reamer 21, between reamer flutes 21b and ring 33, and are directed upwardly from the lower continuation 26-1 of the inner annular space 26 to communication with the lower continuation 37-1, FIG. 1, of the outer annular space 37.

Thus, as the compressed air flows downwardly through annular space 26 and the lower continuation thereof 26-1 and past passages 39, it induces flow of air inwardly through such passages 39 from the outer annular space 37-1 below seal ring 38. This establishes the desired localized circulation, diverting from the nose of the bit 2%) and up through annular space 37-1 some of the air It is.

These functions are peraround the nose of the bit and up through core booster tube 17-1 and the core recovery tube 17.

Whereas there is here illustrated and described a certain preferred construction of apparatus which we presently regard as the best mode of carrying out our invention, it should be understood that various changes may be made without departing from the inventive concepts particularly pointed out and distinctly claimed herebelow.

We claim:

1. in a rotary drilling rig provided with a dual tube drill string adapted to bring core samples to the surface as drilling progresses and including a core bit, concentric outer and inner strings of tubing defining an annular passage leading from the surface to said bit, means for introducing a pressure fluid into said passage near the upper end thereof, and core recovery means at the upper end of the inner string of tubing, the improvement comprising a packer seal ring concentrically swiveled on and outwardly of the outer drive string of tubing above but near the bit, for sealing off the upper portion of the earth bore passage from the lowermost portion thereof during drilling, said outer string having passages therethrcugh, below but adjacent said packer seal ring and establishing communication between said annular passage and the bore hole, and said bit having passages therethrough also establishing communication between said annular passage and the bore hole, the said passages in both instances being so inclined as to establish localized circulation of said pressure fluid through said lowermost portion of the earth bore passage.

2. The improvement set forth in claim 1, wherein a bore hole reamer is additionally provided between the bit and the packer seal ring for smoothing the bore hole walls in advance of said ring.

3. The improvement set forth in claim 2, wherein the first-named passages are disposed between the warmer and the packer seal ring and are directed upwardly from said annular passage to said lowermost portion of the earth bore passage.

4. The improvement set forth in claim 2, wherein the reamer comprises a pipe coupling provided with reamer flutes and a shank extending upwardly therefrom, the packer seal ring being swiveled on said shank.

5. The improvement set forth in claim 1, wherein the first-named passages are directed upwardly from said annular passage to said lowermost portion of the earth bore passage.

6. The improvement set forth in claim 1, wherein the lowermost portion of the inner string of tubing has its inner wall surface grooved longitudinally and rectilinearly to facilitate passage of pressure fluid.

7. The improvementset forth in claim 5, wherein the grooving of the inner wall surface of the inner string oftubing is in the. form of a circumferential series of longitudinally extending, rectilinear grooves.

8. The improvement set. forth in claim 1, wherein the core recovery means comprises a rectilinear core barrel connected to the upper end of the inner string of tubing as a rectilinear continuation thereof.

9. The improvement set forth in claim 8, wherein the core barrel is capped at its upper end and the cap has a vent therein for the pressure fluid.

References Cited in the tile of this patent UNITED STATES PATENTS 

1. IN A ROTARY DRILLING RIG PROVIDED WITH A DUAL TUBE DRILL STRING ADAPTED TO BRING CORE SAMPLES TO THE SURFACE AS DRILLING PROGRESSES AND INCLUDING A CORE BIT, CONCENTRIC OUTER AND INNER STRINGS OF TUBING DEFINING AN ANNULAR PASSAGE LEADING FROM THE SURFACE TO SAID BIT, MEANS FOR INTRODUCING A PRESSURE FLUID INTO SAID PASSAGE NEAR THE UPPER END THEREOF, AND CORE RECOVERY MEANS AT THE UPPER END OF THE INNER STRING OF TUBING, THE IMPROVEMENT COMPRISING A PACKER SEAL RING CONCENTRICALLY SWIVELED ON AND OUTWARDLY OF THE OUTER DRIVE STRING OF TUBING ABOVE BUT NEAR THE BIT, FOR SEALING OFF THE UPPER PORTION OF THE EARTH BORE PASSAGE FROM THE LOWERMOST PORTION THEREOF DURING DRILLING, SAID OUTER STRING HAVING PASSAGES THERETHROUGH, BELOW BUT ADJACENT SAID PACKER SEAL RING AND ESTABLISHING COMMUNICATION BETWEEN SAID ANNULAR PASSAGE AND THE BORE HOLE, AND SAID BIT HAVING PASSAGES THERETHROUGH ALSO ESTABLISHING COMMUNICATION BETWEEN SAID ANNULAR PASSAGE AND THE BORE HOLE, THE SAID PASSAGES IN BOTH INSTANCES BEING SO INCLINED AS TO ESTABLISH LOCALIZED CIRCULATION OF SAID PRESSURE FLUID THROUGH SAID LOWERMOST PORTION OF THE EARTH BORE PASSAGE. 